1. Field of the Invention
The invention relates in general to a hydrophobic composition, and hydrophobic coating layer and fabrication method thereof, and particularly to a removable hydrophobic composition, and removable hydrophobic coating layer and fabrication method thereof.
2. Description of the Related Art
Surfaces of many articles for daily use, consumer electronic products, traffic implements, musical instruments, sports apparatus, porcelain or decorations need to be protected by a hydrophobic treating. However, current methods for forming hydrophobic protecting films needs professional skills, and they would not be carried out by general people. For example, methods for forming hydrophobic protecting films need thermal curing or ultraviolet curing processes. Otherwise, rough surfaces that are hydrophobic are formed by chemical treating processes or etching processes. Therefore, products with hydrophobic surfaces that sold to and used by consumers are often made by manufacturers, since it is hard for consumers to fabricate hydrophobic protecting films
In addition, hydrophobicity of hydrophobic protecting films used for a long period would gradually decrease, and therefore an old hydrophobic protecting film needs to be replaced with a new hydrophobic protecting film. However, current hydrophobic protecting films made by manufacturers are not easily removed directly. Acute methods such as mechanical polishing or heat melting methods are needed to remove the hydrophobic protecting films. The removing methods need extremely professional skills and equipments, and they would easily cause serious damages to materials.
Coating materials that used for forming hydrophobic layers usually contain fluorine, since fluorine that has a low surface potential characteristic would cause a hydrophobic effect. However, Directive 76/769/EEC of the European Parliament severely restrict using of fluorides, such as perfluoro-octanoic acid (PFOA), perfluorooctane sulfonate (PFOS) derivatives, etc. Perfluorooctane sulfonate is one of perfluorinated compounds. Perfluorooctane sulfonate has a good thermostability, and is not easily destroyed in the environment. In addition, perfluorooctane sulfonate is tolerant of water and oil. Perfluoro-octanoic acid (PFOA) and salts of which are one other kind of perfluorinated compounds. PFOA and derivatives of which are applied to treating surfaces of household products such as Teflon Diplomat cooking utensils, convenient food packages, anti-dust fibers and fireproof foam materials. Perfluorinated compounds are harmful to human and animals as they would accumulate in living organic bodies. Thus, the European Parliament has estimated risks, developed safe substitutes, and defined plans for decreasing products and usage.
Hydrophobic protecting films can be obtained by forming rough structures on surfaces of substrate materials and using materials not containing fluorine and having low surface potentials. U.S. Pat. No. 2,786,042 discloses a modified hydrophobic material not containing fluorine (1957). Hydrophobic powders are obtained by modifying surfaces of micro silica structures with C1˜20 silane. U.S. Pat. No. 5,136,074 discloses stable modified powders formed by silylating powders with modifying agents comprising trimethylchlorosilane or t-butyldimethylchlorosilane. U.S. Pat. No. 5,651,921 discloses hydrophobic materials formed by replacing OH groups with organic compounds on silane-modified surfaces of silica materials by using modifying agents comprising organic group-substituted halosilanes, organic group-substituted alkoxysilanes, organic group-substituted silazanes and hydrolyzates. U.S. Pat. No. 6,025,455 discloses modifying OH groups with alkyl functional group on surfaces of silica materials by using materials comprising disiloxane and monosiloxane. The reference teaches using solvents to form a coating material used for forming a hydrophobic layer, and the hydrophobic layer is formed by coating and curing the coating material. U.S. Pat. No. 6,767,984 discloses a composition of a hydrophobic protecting coating material coated on a surface of a car by modifying by grafting a polymer material and silane. In Applied Surface Science, vol. 253, pages 2217˜2221, 2006, a hydrophobic surfaces is obtained by modifying silane with Hexamethyldisilazane. In Applied Surface Science, vol. 255, pages 3600˜-3604, 2009, a transparent and hydrophobic layer is obtained by modifying a surface of silane material with Trimethylethoxysialne compound. In Journal of Colloid and Interface Science, vol. 332, pages 484˜490, 2009, a hydrophobic layer that can sustain a high humidity environment for one month is obtained by using hexamethyldisilazane and methyltrimethoxysilane.
WO 2008/153687 discloses a coating composition with powders which surfaces are modified with materials having a low surface potential. A hydrophobic layer can be formed by directly coating the coating composition on a surface of a substrate material. However, the hydrophobic layer has a weak adhesion strength and non-stable problem. TW I310779 discloses using epoxy resin as hydrophobic powders and adhesion agent applied between substrates. The hydrophobic layer is attached to the substrate with strong adhesion strength and is not easily removed. TW 96121473 discloses using a polyacrylic ester as a dirt-proof and waterproof adhesion agent that has a high transparency and durable characteristic. The hydrophobic layer formed by using the coating material is hardly removed. The hydrophobic layer is usually removed with professional skills and equipments, such as mechanical polishing or heat melting method.
In some cases, paraffin having a hydrophobic characteristic intrinsically is used to fabricate a hydrophobic protecting layer. However, such coating material easily has non-uniformly-mixing problem with powders. In addition, hydrophobic powders are fully covered by the paraffin, and thus they could not perform the hydrophobic characteristic. Therefore, a hydrophobicity of the hydrophobic layer is extremely decreased.